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Tag Archives: Databases

Work with Parallel Database Streams using Custom Thread Pools

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Parallel Database Streams In my previous post, I wrote about processing database content in parallel using parallel streams and Speedment. Parallel streams can, under many circumstances, be significantly faster than the usual sequential database streams.             Speedment is an open-source Stream ORM Java Toolkit and Runtime Java tool that wraps an existing database and its tables ...

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Using Named Database Locks

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In a beginner’s guide to concurrency, I mentioned advisory locks. These are not the usual table locks – they are table-agnostic, database-specific way to obtain a named lock from your application. Basically, you use your database instance for centralized application-level locking. What could it be used for? If you want to have serial operations, this is a rather simple way ...

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How To: Insert and Read From a Database using Json

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In this article we will create a plugin for Speedment that generates serialization and deserialization logic using Gson to make it super easy to map between database entities and JSON strings. This will help to showcase the extendability of the Speedment code generation while at the same time explore some of the cool features of the Gson library. Speedment is ...

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AutoCommit in PostgreSQL’s psql

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One potential surprise for someone familiar with Oracle database‘s SQL*Plus when being introduced to PostgreSQL database‘s psql may be psql‘s default enabling of autocommit. This post provides an overview of psql’s handling of autocommit and some related nuances. By default, Oracle’s SQL*Plus command-line tool does not automatically commit DML statements and the operator must explicitly commit these statements as part ...

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SPOOLing Queries with Results in psql

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SQL*Plus, the Oracle database‘s command-line tool, provides the SPOOL command to “store query results in a file.” The next screen snapshot shows SPOOL used in SQL*Plus to spool the listing of user tables to a file called C:\pdf\output.txt.                 Both the executed query and the results of the query have been spooled to ...

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SQL for Application Developers

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“SQL? Isn’t that just something my ORM tools use?” Often application developers can and should remain at least one level removed from SQL. JPA and the Entity Framework each provide more abstract (and OO-friendly) query languages, and it’s often unnecessary to write any queries at all. If you ever diagnose production support issues, though, being proficient with SQL can greatly ...

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Agile Databases

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Any project following an Agile methodology will usually find itself releasing to production at least 15 – 20 times per year. Even if only half of these releases involve database changes, that’s 10 changes to production databases so you need a good lean process to ensure you get a good paper trail but at the same time you don’t want ...

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Solving Problems with the Right Technology: Hadoop and RDBMS

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In some circles today there is a sort of ‘Hadoop vs. RDBMS’ debate ongoing. Often the discussion casts Hadoop as the obvious heir apparent in the data processing world, with RDBMS cast as your father’s Oldsmobile. This debate is somewhat misdirected and the discussion could lead organizations away from the strategy they really should be following, namely a strategy of ...

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A tale of troubleshooting database performance, with Cassandra and sysdig

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Gianluca Bordello is an engineering manager at Sysdig, where he wears many hats. He’s a core developer of sysdig, an open source troubleshooting tool for Linux and containers, and spends his days dealing with backend development, performance analysis and cloud infrastructure management. Introduction As far as databases go, I’m a  huge fan of Cassandra: it’s an incredibly powerful and flexible ...

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Using Oracle AQ via Java 8 Streams

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One of the most awesome features of the Oracle database is Oracle AQ: Oracle Database Advanced Queuing. The AQ API implements a full fledged, transactional messaging system directly in the database. In a classic architecture where the database is at the center of your system, with multiple applications (some of which written in Java, others written in Perl or PL/SQL, ...

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